Safety seat belts



Dec. 3,' 1968 H. G. LINDEROTH 3,414,322

SAFETY SEAT BELTS Filed Oct. 18, 1966 United States Patent 3,414,322 SAFETY SEAT BELTS Hans G. Linderotla, Paris, France, assignor to AB Industrifjadrar, Monsteras, Sweden Filed Oct. 18, 1966, Ser. No. 587,515 Claims priority, application Sweden, Oct. 22, 1965 13,676/ 65 6 Claims. (Cl. 297389) ABSTRACT OF THE DISCLOSURE A safety seat belt for vehicles comprising a shoulder strap and a hip strap with the shoulder strap having a considerably greater plastic elongation than the hip strap.

This invention relates to a safety seat belt for automobiles, aircraft and seacraft. The seat belt is of the type comprising a strap adapted to extend across the thorax of the person to be strapped in the seat, and a strap adapted to extend across the hip portion of said person.

Accordingly, the present invention is directed to a safety seat belt with hip and shoulder straps wherein the shoulder strap passing across the thorax has considerably greater stretchability than the hip strap. The invention provides a safety belt which distributes the forces arising at the retardation of the vehicle proportionally to the ability of the thorax and the hip portion to withstand load. The hip portion will thus take up the major part of the load.

These and further features of the invention will become apparent from the following detailed specification in which reference is made to the accompanying drawing wherein FIGS. 1 and 2 diagrammatically illustrate socalled three-point type safety seat belts of single and two strap construction respectively.

In FIGS. 1 and 2, strap 1 is adapted to lie across the thorax of the person to be strapped in the seat, and 2 denotes the strap which is to lie across the hip portion of this person. In the example chosen the strap 1 is adapted to extend in the manner of the cordon of an order obliquely across the thorax of the person to be strapped to a fastening 3 above his one shoulder. In the following the said strap 1 will therefore be termed shoulder strap. The hip strap 2 is to extend across the hip portion of the person to be strapped from one side of the seat to the other side thereof. At the one side the hip strap 2 is for permanent anchoring to a fastening 4 and for detachable anchoring at the other side. To this end, the strap 2 is equipped with a buckle 5. Also the shoulder strap 1 is secured to the buckle 5 with the end facing away from the fastening 3. The interconnection of the straps 1, 2 with the buckle 5 is such that the straps will be independent of each other. A pull at one strap does not therefore effect the other strap. However, the straps 1, 2 are of individually adjustable length to permit adjustment of the safety seat belt to the size of the person using the seat belt.

According to the invention, the shoulder strap 1 has considerably greater stretchability and elongation, respectively, than the hip strap 2. The shoulder strap 1 should have at least twice as great a stretchability as the hip strap 2. It has even proved suitable to give the shoulder strap 1 three to four times as great a stretchability as the hip strap 2.

In practice the shoulder strap 1 should have an elongation of 25-45%, preferably about 35%, of the original length at a load of 1250 kilograms on said strap. This elongation is independent of the width of the strap which should, however, be at least 47 mm. wide. The corresponding elongation for the hip strap is 5l5%, preferably about of the original length.

For both the shoulder strap 1 and the hip strap 2 the recovery at a load between 1250 kilograms and 1000 kilograms should not exceed 1%, while the recovery at a load of 500 kilograms should not exceed 7%. In other words, it is important that the straps 1 and 2 under a great load are subjected to permanent deformation with the ability for energy absorption through this permanent deformation known as plastic elongation.

The shoulder strap 1 and the hip strap 2 are suitably formed by two entirely separate strap portions which are each connected individually to the buckle 5 as seen in FIG. 2. Alternatively, the shoulder strap 1 and the hip strap 2 may be formed by a single strap the different parts of which possess different stretchability as shown in FIG. 1. The change of the stretchability can advantageously be attained through the weaving technique employed for the strap.

The invention is essentially concerned with safety seat belts now in general use, i.e. such safety seat belts in which the shoulder strap 1 and the hip strap 2 are essentially of the same length. For exceptionally short belts, i.e. such having fastenings to the vehicle seat, and for exceptionally long belts, e.g. such as have the lateral fastening placed in the fioor structure, the figures must of course be changed with due regard to the differences in strap length since the forward movement of the body is essential. In other words, the stretchability of the straps is decisive.

While the invention has been described above and shown in a preferred embodiment chosen by way of example it is understood by those skilled in the art that the invention is not limited thereto but permits of modification within the scope of the appended claims.

What I claim and desire to secure by Letters Patent is:

1. A safety seat belt for automobiles, aircraft and seacraft, comprising a shoulder strap adapted to extend across the thorax of the person to be strapped in the seat, and a hip strap adapted to extend across the hip portion of said person, said shoulder strap having considerably greater plastic elongation than said hip strap.

2. A safety seat belt as claimed in claim 1, wherein the shoulder strap has at least twice as great a plastic elongation than the hip strap.

3. A safety seat belt as claimed in claim 1, wherein the shoulder strap has a plastic elongation between three to four times as great as the hip strap.

4. A safety seat belt as claimed in claim 1, wherein the shoulder strap has an original elongation before recovery of 25-45%, preferably about 35%, of the original length at a load of 1250 kilograms while the hip strap has an original elongation before recovery of 5l5%, preferably 10%, of the original length at a load of 1250 kilograms.

S. A safety seat belt as claimed in claim 1, wherein the shoulder strap and the hip strap are two entirely separate strap portions.

6. A safety seat belt as claimed in claim 1, wherein the shoulder strap and the hip strap are formed by a single strap the difierent portions of which have different plastic elongation.

References Cited UNITED STATES PATENTS 2,649,145 8/ 1953 McCarthy 2973 86 2,823,046 2/1958 Banta 297389 2,850,082 9/1958 Day 297386 2,880,789 4/1959 Leibinger 297385 2,888,063 5/1959 Rose 297387 FOREIGN PATENTS 580,203 7/1957 Canada.

JAMES T. MCCALL, Primary Examiner. 

